Typically, speaker systems have been used to acoustically and electronically reinforce amplified sound reproduction of musical and other audio performances, Whether by live instrumentation or by playback of recorded material. Such amplifying systems may include speaker enclosures utilizing single or multiple drivers with various baffling and acoustical absorption methodologies to enhance the tone and constructed as stackable rectangular enclosures with or without tuned ports. Conventional rectangular speaker cabinets, especially when loaded with multiple speakers (e.g., the common so-called “4×12” enclosure), may exhibit a narrow beam of sound originally intended to project the sound in a “long throw” manner during live performances. Such amplifying systems may also include electronic circuitry that may enhance the tonal quality (i.e., equalize the sound with tone shaping controls, add desirable harmonic distortion and reverberation effects being common examples) and amplify the signal sufficiently to drive an output device such as a speaker.
Musical instrument performance amplifiers traditionally utilize vacuum tubes as the active circuit elements. Other known musical instrument amplifiers utilize solid-state devices, such as NPN transistors or PNP transistors, field effect transistors, and the like. Further, other known musical instrument amplifiers utilize digital signal processing to model, or mimic, the sonic characteristics of vacuum tube circuitry. It will be appreciated that the methodologies disclosed in the present invention shall include all known or unknown methods of signal amplification and are not limited exclusively to vacuum tube circuit elements.
Examples of known musical instrument amplifiers offered for sale include the “AC30” as sold under the VOX trademark, “Deluxe Reverb” as sold under the FENDER trademark, “2203” as sold under the MARSHALL trademark, and the “Spider Valve” as sold under the LINE6 trademark. Each of the above amplifiers share a common goal in providing enhanced sound quality in an easy to use package. The AC30, Deluxe Reverb and the 2203 share a vacuum tube approach to signal amplification and are considered by knowledgeable musicians to be an important part of the historic sonic fabric of live and recorded popular music. The Spider Valve is unique in that it utilizes digital processing in the preamplifier to mimic the historical sound signatures of the previously discussed amplifiers while relying on vacuum tubes as the active circuit element for driving an output transformer attached to a speaker.
It is known in the art to utilize an amplifier combined with a speaker to produce a desirable electric guitar sound. One such configuration combines these elements in one assembly and known as a “combo” amplifier (i.e., amplifier and speaker or multiples of speakers assembled in one housing). Another configuration divides a system into separate components such as an amplifier (often referred to as an “amp head”) for electrically amplifying the signal sufficiently enough to drive a separate acoustical energy transducer, such as a speaker mounted in an enclosure in such a way as to facilitate the radiation of sound wave energy (often referred to as a “speaker cabinet”). Although a variety of speaker sizes exist, the most common speaker size associated with electric guitar features a 12-inch cone due to its inherent favorable sound characteristics in relation to the frequency demands when amplifying electric guitar signals. It will be appreciated that a 12-inch loudspeaker radiates lower frequencies at the outer edges and radiates higher frequencies in the narrow portions around the center of the cone and may produce a narrow beam of bright sound (i.e., sound with emphasized high-frequency content) as perceived by anyone located within this dispersion area. When making use of these components, it is common to stack the amp head on top of the speaker cabinet loaded with a single or multiple 12-inch speakers. Most common among guitar speaker cabinets is the “4×12” (i.e., a quantity of four 12-inch speakers mounted in the same enclosure). Musicians may further describe such a system as a “half stack” (i.e., one amp head and one speaker cabinet) or as a “full stack” (i.e., one amp head and two speaker cabinets). It will be appreciated that when multiple 12-inch speakers are combined, numerous high-frequency sound beams are being transmitted by the system and may result in poor sound quality (i.e., harsh and brittle, comb-filtered and muddy) in several areas on stage as well as in the audience.
Traditionally, guitarists perform live concerts with half-stacks, full-stacks and even multiple stacks of amplifiers. In contrast, modern sound reinforcement, production and staging practices have begun to emphasize cleaner stages (i.e., fewer amplifiers on stage) to both enhance the production (i.e., cleaner sight lines allow for greater use of video screen production effects) and reduce sound pressure levels (SPL) as well as beaming guitar sound waves originating from the stage. The benefits of a lower stage volume may include a reduction in hearing related injuries and an improvement in the overall sound quality as perceived by the audience. In order to facilitate this new practice, innovative wireless in-ear monitoring technologies has been developed by companies such as Shure, Inc. and Sennheiser Electronic Corporation. These wireless inear monitor systems are comprised of a transmitter, portable receiver (i.e., body worn, battery powered pack) and miniature earphones. In practice, a musician employing an inear monitoring system may be able to monitor both his performance and that of the other musicians while controlling the overall mix (i.e., blended of sound of himself in relation to the other musicians) and overall volume via the on-board controls of the portable body-pack receiver. To further enhance the performance of in-ear monitors, guitar amplifiers are occasionally placed below the deck (i.e., off to the side or under the actual stage assembly). Accordingly, there is a need for guitar amplifiers that specifically produce a high-quality sound, at reasonable volumes, with a reduced stage footprint (i.e., the space occupied by the equipment on stage), with a reduced harsh beam of sound, while producing a sound and feel that closely matches the various large-format amplifiers previously relied upon.
Guitarists use instrument amplifiers capable of producing new sounds as well as high-quality approximations of signature vintage amplifier tones. Historically speaking, original vintage equipment was often under powered which led to the practice of turning them up to maximum volume. Under these operating conditions, vintage amplifiers would often distort the signal which guitarists found beneficial to the sound quality. This created a problem for the musician: achieving a distorted sound at lower volumes. Numerous approaches exist and include master volume controls, “dummy” speaker load devices that “soak” up power, power regulators and power diversion circuitry and so on.
The problems associated with all of these various methods include undesirable changes in the sound quality and or the sensitivity or “dynamic feel” of the amplifier, as well as the complexity of user interface. Even something as simple as two knobs often requires the customer to adjust the user interface in difficult-to-replicate ways in order to achieve an acceptable sound.
Each of the various approaches to reducing overall volume have some measure of limited effective operating range such as 10-20%. While it is possible to reduce the perceived volume level in most cases all the way down to “zero” sound the perceived sound and feel of the amplifier worsens at settings beyond this operating range. The flatness in volume reduction is due to the reliance on one “magic-bullet” circuit do all of the work necessary to reduce the volume.
Further, guitar players have become even more conscious to their perceived output power needs and make their amplifier selections based partially on how much power the amplifier is dissipating or is perceived to dissipate in terms of overall sound output. Guitar players categorize amplifiers at 10 to 20 watts, 30 to 40 watts, 50 watts and 100 watts. Guitarists want a 10 watt amp automatically rule out all amps with power in excess of 20 watts—even if those amplifiers feature a master volume control. Excess power is perceived as waste is commonly rejected—especially with today's manufacturers offering a wide range of power options. The excess power designed into the amplifier can distort the signal at lower volumes.